Abstract
The article presents research data of concrete with chemical admixtures for precast concrete. To the additives are hardening accelerators, systems-based accelerators, plasticizers and air-entraining additives. The authors studied the effect of the addition of electrolytes (NаСl, Nа2SО4 СаСl2, Са(NO3)2), complex additives (on the basis of the electrolytes and plasticizers, air-entraining additives SPD and mikrokremnezema) on properties of concrete, strength of concrete steamed and some of its properties. By accelerating the effect of electrolyte additives studied were located in the sequence: СаСl2 > NаСl > Nа2SO4 > Са(NO3)2. It is noted that the increase of concrete strength with electrolytes increases with decreasing the duration of heating and the content of aluminates in Portland cement, which allows for 40...50% reduction in the warm-up of concrete or 5...15% of cement consumption. Complex agent (on their basis), irrespective of the Mineralogy of the cement is more efficient and reduce the cement consumption by 10...15%, superplasticizers up to 20%, but long-term modes and regardless of the type of Portland cement. The article contains a material with strength in different curing regimes, the indicators of reduction of consumption of cement and frost resistance of concrete with the introduction of air-entraining additives. Empirical formula to calculate the reduction of the duration of isothermal heating regime during heat treatment of concrete.
Highlights
The authors studied the effect of the addition of electrolytes (NаС1, Nа2SО4, СаСl2, Са(NO3)2), complex additives on properties of concrete, strength of concrete steamed and some of its properties
By accelerating the effect of electrolyte additives studied were located in the sequence: СаСl2 > NаС1 > Nа2SO4 > Са(NO3)2
It is noted that the increase of concrete strength with electrolytes increases with decreasing the duration of heating and the content of aluminates in Portland cement, which allows for 40...50 % reduction in the warm-up of concrete or 5...15 % of cement consumption
Summary
Авторы статьи изучали влияние добавок электролитов (NаС1, Nа2SО4, СаСl2, Са(NO3)2), комплексных добавок (на основе пластификаторов и электролитов, воздухововлекающей добавки СПД и микрокремнезма) на свойства бетонной смеси, прочность пропаренного бетона и некоторые его свойства. В статье содержится материал с показателями прочности по различным режимам тепловлажностной обработки, приведены показатели сокращения расхода цемента и морозостойкость бетона при введении воздухововлекающих добавок. Авторами статьи изучалось влияние добавок электролитов (NаС1, Nа2SО4, СаСl2, Са(NO3), комплексных (на основе пластификаторов + электролиты), воздухововлекающей добавки СПД и микрокремнезема на свойства бетонной смеси, прочность пропаренного бетона и некоторые его свойства. Из прироста прочности бетонов на быстротвердеющем высокоалюминатном (С3А > 10 %), среднеалюминатном (С3А = 6...10 %) и низкоалюминатном портландцементах (С3А < 6%), пуццолановом и щлакопортландцементе сразу после прогрева с добавками возможно сократить длительность тепловой обработки бетона на З0 %. Проведенные исследования показали,что для практических целей при применении добавок ускорителей твердения с целью сокращения расхода цемента увеличенное значение В/Ц бетона целесообразно определять по формуле: Таблица 1 Прочность пропаренного бетона с добавками ускорителей твердения
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